what is the point of telling add_filter how many parameters you want passed to the function?

The reason is that you can register native PHP functions as callbacks. Passing more parameters to them then they expect will raise a warning.

Imagine a filter that can pass 6 parameters and trim() as callback. PHP would now raise an error:

Warning: Wrong parameter count for trim() in …

Some custom callbacks might also change their behavior depending on the amount of passed arguments. That’s surely not good code, but such code exists, and it would break if WP would change its current behavior now.

Related Posts:

  1. Where is the best place to use add_filter
  2. Edit plugin without hooks in functions.php
  3. Using add_filter inside another class
  4. How to list the Hooks and order of execution in current loading page? [duplicate]
  5. Pass A Value From Outside To A Plugin Variable
  6. Failed to invoke other hook from the init hook
  7. How can I filter blog name?
  8. Custom preview_post_link not working for draft post
  9. Add Fields with Sub-Fields to WP Job Manager
  10. Determine plugin name from within plugin_action_links filter
  11. merging an array to an existing array using add_filter
  12. Creating a plugin to sanitize comment and the url field before display only
  13. How to find the origin of a file upload from within wp_handle_upload?
  14. White page by using filter template_include
  15. How to check current user before all actions and filters?
  16. Create a navbar filter that filters by a custom field
  17. Passing an array from shortcode-function to filter-function
  18. Get Time Taken By Each Action Hook in WordPress
  19. qTranslate remove default directory from link
  20. How to change the name of the “edit my profile” link in the WordPress admin backend
  21. Proper way to replace the_content only for pages created by custom plugin
  22. add_filter doesn’t work
  23. Redirect to another page using contact form 7? [closed]
  24. Check if variable is set in filter
  25. Check filter defined or not?
  26. Add a function call after content automatically?
  27. How to add filter for wordpress plugin?
  28. How to use add_action for multiple instances of the same class
  29. How to append new form elements in “Add New” form of Users in WordPress admin panel?
  30. Want to create custom design of progress indicator in wpforms
  31. Add hook after content without formatting
  32. Using OR Condition with facetwp facets
  33. 500 Internal server error wp_handle_upload_prefilter
  34. Nested Actions and Filters
  35. Remove action added in plugin class from theme
  36. Using multi-dimensional array with filter
  37. Can I add content before post content without using the_content filter
  38. WordPress Add advertising ads befor and after content with periority [closed]
  39. trying to create simple plugin to filter categories from all authors
  40. shortcode which is introduced into entry the blog, and appears in side bar
  41. How do i get all author posts on custom post type list
  42. Unable to pass arguments from plugin form to filter hook using ajax, the data is transferring via ajax but unable to pass as arguments in filter hooks
  43. How can we extent core/group or cover block?
  44. Uninstall, Activate, Deactivate a plugin: typical features & how-to
  45. How to only hook on Single.php after content?
  46. How to stop showing admin notice after close button has been clicked
  47. Add rewrite rule to permalink structure
  48. How to save the values of checkbox to the register setting?
  49. Handling jQuery Component Collision
  50. How to get Login Error messages on a custom template
  51. Finding WordPress sites using my plugins
  52. Enqueue style inside shortcode but its loaded at the bottom of page (before footer scripts)
  53. WordPress Plugin as ‘Library’ From Abstract Application?
  54. Claim Listing functionality – how to send email to users when their claim has been approved or denied
  55. Creating a theme option page?
  56. WordPress 4.0 Cookie Authentication to avoid nonce error when publishing a post and page
  57. Add post thumbnail from external image with plugin
  58. Does the ‘nav_menu_css_class’ filter accept 2 or 3 arguments?
  59. Where is the source code that makes the “all” array grabs filters in the $wp_filter?
  60. How to Build a Movie Library in WordPress 3.x
  61. do_action and hook methods
  62. Options page not displayed under Settings menu
  63. Is it possible to add an action to the currently running action?
  64. How to include and use custom class files in plugin?
  65. How to prevent action in ajax request, when in admin side?
  66. Only execute jQuery function(on document ready) on the page has shortcode from plugin [duplicate]
  67. How can I get full attachment url from wp_get_attachment_metadata?
  68. unzip a folder on specific location and delete the zip file
  69. Reposition Woocommerce Message
  70. Custom plugins/Manipulated plugins: Always a terrible idea to inherit these types of WP sites that discourage updates? [closed]
  71. Accessing GET variable named ‘error’
  72. Demystifying and understanding shortcode nomenclature
  73. How to modify shortcode attributes with data from current post
  74. download_url() appears as grey icons
  75. Plugin not appearing after uploading it via FTP
  76. How can I add an options page for my class based plugin?
  77. Sending WP posts to external API
  78. Any Short code Availble for Get Post List With Thumbnail Plugin?
  79. Changing labels of status filters for post grid
  80. Where to call add_shortcode function in WordPress Plugin Boilerplate?
  81. Plugin version is not showing up in wordpress.org plugin directory
  82. Any hook for pre-plugin-update -either bulk or single plugin update
  83. wp_create_nonce function doesn’t work inside a plugin?
  84. Own plugin corrups plugin-activation
  85. wordpress plugin is not activating from widget
  86. When to load auto-login code?
  87. CSV file generation failing
  88. finding whether request is for post, and post id
  89. Modifying the comments section through a plugin regardless of theme
  90. How to get specific setting by settings_fields()?
  91. Creating a custom post type, adding custom meta fields, preventing all future editability of posts of this type
  92. Prevent duplicate records in plugin table
  93. How to fetch products with the price in a page on woocommerce using a form or live search with php
  94. Owl Carousel2 image not displaying full width when using Stretch row and content, Stretch row and content(no padding) in wordpress
  95. Creating a Callback URL for WordPress Woocommerce to update Order Status
  96. Best way to initiate a class in a WP plugin?
  97. How to replace WordPress Media Upload Window with user’s device window?
  98. Buidling a translate plugin for wordpress
  99. Force language in translate function
  100. wp_footer hook only working on homepage not in other pages